This invention relates to a pneumatic rotary tool, and more particularly to an air inlet valve construction for such a tool.
The invention has been developed as an improvement on the pneumatic rotary tool disclosed in U.S. Pat. No. 5,918,686 issued Jul. 6, 1999, entitled Pneumatic Rotary Tool, incorporated herein by reference, hereinafter referred to as the ""686 patent.
In the tool disclosed in the ""686 patent, the flow of air to the air motor thereof is under primary control of a trigger-operated air valve (indicated at 65 in the ""686 patent), which is referred to in the patent as the primary air valve. Paraphrasing lines 37-45, column 7 of the patent, in using the tool the operator, using his index finger, squeezes the trigger to open the valve and the speed at which the tool operates depends on how far inward he pulls the trigger. While the tool has been generally satisfactory, inexperienced operators may encounter some difficulty in squeezing the trigger to attain and maintain a relatively low speed when that is needed for the work to be performed.
Accordingly, among the several objects of this invention may be noted the provision of a tool of the type shown in the ""686 patent improved to the extent of making it easier for the user to attain and maintain a low speed of the air motor, whereby the user may readily attain and maintain a particular low-speed setting or a high speed setting, as needed for the job at hand; the provision in the tool of valve means including the primary air valve of the ""686 patent invention for the dual stage speed purpose; the provision of a pistol-grip type of tool such as shown in the ""686 patent wherein the pull on the trigger controls the speed setting; and the provision of valve means for the stated purpose of economical construction and capable of economic assembly.
In general, a pneumatic rotary hand tool of this invention comprises a housing having an air motor therein, the housing having an inlet passage for flow of air to the motor for driving it and valve means for controlling the flow of air through the inlet passage. The inlet passage has an upstream facing valve seat, the valve means comprising members in the passage upstream of the seat one of which has a stem extending downstream therefrom past the seat. A spring biases said members in downstream direction to a closed position with respect to the seat. The stem extends generally axially in said passage in said closed position of said members. A deflector for the stem is operable by one holding the tool for deflecting the stem angularly from said generally axial position to a first angularly deflected position wherein said valve members establish flow of air to the motor at a relatively low rate for low-speed operation thereof and further to a second farther angularly deflected position wherein said valve members establish flow of air to the motor at a relatively high rate for high-speed operation thereof.
Other objects and features will be in part apparent and in part pointed out hereinafter.